【正确答案】 D

【答案解析】[解析]从文章第一段的They had seen Mrs. Cibson and Cynthia off to London. She wished her step-mother…，第三段的We're just been seeing my wife and her daughter off to London和one of the Doctor's patients中可推出Mr. Gibson是一个医生，Mrs. Cibson是他的妻子。